Responsive photonic materials are of great interest due to their broad applications relevant to the controlling of colors. Being efficient and inexpensive, colloidal self-assembly has been widely studied for the fabrication of photonic crystal structures, especially for applications that can tolerate defects. While many studies have focused on tuning the refractive index of the components or the periodicity by incorporating active materials that can respond to environmental changes, in accordance with an exemplary embodiment a magnetically tunable photonic structure by assembling uniform superparamagnetic (SPM) colloidal particles into one-dimensional (1D) chain-like arrays in various liquid media has recently been developed. The dynamic ordering of the magnetic colloids with controllable periodicity along the direction of the external field renders the system a fast, fully reversible photonic response across the visible-near-infrared spectrum. By taking advantage of the magnetic property, in accordance with another exemplary embodiment, a tunable photonic materials whose properties can be manipulated by changing their orientation with external fields has been developed. This was achieved by embedding aligned chains of periodically arranged SPM particles in polymer microspheres so that their relative orientation and correspondingly the diffraction property can be tuned by rotating the external magnetic fields. The division of bulk photonic crystals into many small units tens of micrometers in size brings the benefits of easy fabrication, actuation and broader applications, as the color of these units can be controlled individually or collectively as needed by using external magnetic fields. It can be appreciated that to extend this principle to the fabrication of magnetically responsive photonic structures with significantly reduced dimensions so that color manipulation with higher resolution can be realized has be achieved. The ideal case is to fix individual magnetic particle chains. This will produce the smallest possible photonic nanostructures that can effectively diffract at visible spectrum. In addition to color displays, these optically active magnetic nanochains may find great use in fields such as bio- and chemical sensing and biomedical labeling and imaging.